The protection effectiveness of traditional Lightning Strike Protection (LSP) for composite rotor blade of helicopter can be diminished due to the explosion risk in overlapping attachment under lightning strike, so a new protection method based on Air Breakdown and insulating adhesive layer (AB-LSP method) was designed to avoid it. In this study, a numerical method was developed to simulate the electrical breakdown, and verified by experiment results. Based on this method, a Finite Element Model (FEM) was established to investigate the effect of two factors (breakdown strength and initial ablation temperature of adhesive layer) on the LSP effectiveness. The results show that the breakdown strength impacts more to the ablation damage in composite than that of high-temperature resistance. Then, another FEM was established to predict the ablation damage by lightning strike in the AB-LSP method protected composite rotor blade. The mechanisms and potential key parameters (magnitude of lightning current, discharge channel location, adhesive layer thickness, and air gap width) that could affect the protection effectiveness were analyzed. The introduction of air breakdown changes the current conduction path and reduces explosion risk. After rational design, this method can offer effective lightning protection for composite helicopter rotor blade and other composite structures.

The damage distribution of the same type of aircraft in similar service environments should be similar. Based on this assumption, to perform the maintenance and repair of aircraft composite structures, the damage of composite structures in a certain type of aircraft were investigated. The time-varying damage distribution model was established and verified based on the damage of a 16-aircraft fleet. The results show that the quantitative proportions of structural damage are 74% for skin delamination, 22% for stringer delamination and 3% for stringer-skin interface debonding. The amount of structural damages increases linearly with service time while the proportion of different damages does not change. As the service time increases, the geometric parameter distribution of damage for the same type of aircraft gradually converges, which can be approximated using the same function. There are certain differences in the proportion and geometric parameter distribution of damages among different components and locations, and the differences do not change over time.

The gap between the main wing surface and the movable wing surface might have a certain impact on the flight performance of the aircraft. The application of the gap-sealing structure will improve the surface smoothness of the wing while achieving effects such as increasing lift, reducing drag, and optimizing operation. This article compares various sealing structure design forms and divides them into two categories: relying on materials and relying on mechanisms. The benefits and drawbacks of each category are examined.The sealing structure products of several aviation parts companies are compared. Analysis is done on intricate designs like wear-resistant free ends. Design suggestions are provided at last, such as rapid disassembly and repair, limitation for the range of the structural stiffness, and a combination of simulation and experiment while designing.